Rotary lip knife for bag machines



Aug. 12, 1941. w. BocHow 2,251,975

ROTARY LIP KNIFE FOR BAG MACHINES Filed April 18, 1940 2 Sheets-Sheet l x sme- E 1\ gv i- Q 00 600 0 N KQKZ INVENTOR V/IATEE Boa/vow ATTORNEY w; BOCHOW ROTARY LIP KNIFE FOR BAG MACHINES Aug. 12, 1941.

Filed April 18, 1940 -2 Sheets-Sheet 2 INVENTOR 75/2 Each/ow.

ATTORNEY Patented Aug. 12, 1941 UNHTED STATES TNT OFFICE ROTARY LIP KNIFE FOR BAG MACHINES Application April 18, 1940, Serial No. 330,233

6 Claims.

The present invention relates to bag machines in which a web of paper is folded into a tube and successive bag sections are severed from the tube in a continuous operation.

One of the objects of the invention is to produce a better appearing bag.

Another object is to render the machine less noisy.

A further object is to provide means whereby the severance of the bag walls is accomplished with greater ease.

In accomplishing the above objects, one of the features of the invention relates to the provision of a rotary lip knife having a serrated edge but the teeth are much finer than the teeth of lip knives heretofore used.

A further feature relates to the provision of a rotary lip knife in such timed relation with the striker bar that one bag wall is severed in advance of the other thereby providing an easier cut-off, tending to reduce the noise incident to operation, and to increase the speed of production.

A further feature relates to the provision of a striker bar arranged to come into kissing contact with the cutting edge of the former whereby the lower tube wall is severed at the time the striker bar passes the former. By reason of this construction it is possible to have finer teeth on the former than usually found practically feasible by methods and machinery heretofore employed.

Further features'and advantages will become apparent from the following detailed description and claims when taken in connection with the accompanying drawings in which:

Figure 1 is a central longitudinal section showing the invention applied to a bag machine of known construction and showing so much of the old elements as are necessary to an understanding of the present invention;

Figure 2 is an enlarged view of some of the elements shown near the left end of Figure 1;

Figure 3 is a diagrammatic plan view illustrating the preliminary slitting of the web, the folding of the same into a bag tube and a severed section;

Figure 4 is a sectional view somewhat similar to Figure 2 but showing'a feature of the invention not shown in Figure 2;

Figure 5 illustrates the appearance of a severed bag section such as would result from the mechanism shown in Figure 2;

Figure 6 is a section taken on the line ii-6 of Figure 4;

Figure 7 shows the upper portion of a severed tube section as produced by the mechanism shown in Figure 4; and

Figure 8 is a detail sectional view showing the position of the parts at the moment of severance of the lower tube wall.

The type of bag adapted to be produced by the machine of the present invention is of the general type illustrated and described in the patent to George W. Poppe granted March 31, 1931, $14,798,168.

The machine of the present invention operates in a manner similar to the machine disclosed in said patent insofar as makingpreliminary cuts in a web which cuts determine the side edge of the closing flap of the finished bag; folding the web into a tube and feeding the tube through the machine. The machine of the present invention, however, differs from the machine of said patent in the manner in which the bag tube sections are severed from the tube.

Referring to Figure 1, there is provided a supporting frame work 2 and extending transversely between the side members of this frame work are a number of shafts for operating the various mechanisms all of which are suitably driven from shaft 4. This shaft is provided with the usual sprocket indicated merely by dotted lines in Figure 1 which sprocket drives a sprocket chain 6 which passes around a sprocket 1 carried by shaft 8. This shaft carries a gear 9 meshing with a similar gear I0 on shaft H. The latter shaft carries a sprocket 12 which drives a sprocket chain It which passes about a sprocket I5 carried by a shaft [6. The shaft It carries knives I8 of which one only is shown. These knives may be in the form of dies and are similar in construction and function to the dies 58 shown in Figures 1 and 2 of the aforesaid Poppe patent. The paper from which the bags are to be made passes from a roll 20 in the form of a web '22, the web being guided by rollers 23 to roller 24 which is preferably of hardened steel. The roller 24 reverses the direction of movement of the web, which after passing the roller 24 engages under the heel 26 of the former 28. As the web passes about the roller 24 it receives a line of paste near one edge which line of paste is supplied by a paste disc 39. During the passage of the web over the roller 24, the knives [8 make cuts indicated at 32, Figure 3. As the web passes under the former, it is folded over onto it and one longitudinal edge is pasted to the other edge to form a bag tube as clearly indicated in Figure 3.

The usual feed rollers 33 are also provided for advancing the web and the folded tube.

All of the mechanism heretofore described is found in a bag machine such as that illustrated in the aforesaid Poppe patent.

As shown in said Poppe patent, the tube is severed by a striker bar delivering a sharp blow to the under side of the tube and severing the lower wall of the tube against the serrated edge of the former and the upper wall of the tube against the edge of a lip knife indicated at 36, Figure l of said patent. By the mechanism shown in said patent, the severance of both tube walls is substantially simultaneous. Due to this manner of severance the teeth on the end of the former and the teeth of the lip knife were of necessity made of such size as to permit this manner of severance of the bag walls.

According to the present invent-ion, a rotary lip knife takes the place of the stationary lip knife of the prior art. Referring particularly to Figure 2, there is provided a cylinder 34 suitably supported in the side frames of the machine as shown in Figure 6. This cylinder carries a lip knife 36 having a straight edge 31 provided with fine serrations. The cylinder 34 is driven from the shaft 4 by means of a gear 38 carried by said shaft which gear transmits its motion to the cylinder 34 through the medium of two idler gears 39, see also Figure 2. Thus while the gear 38 is rotated in an anti-clockwise direction, the cylinder 34 is rotated in a clockwise direction. The shaft 4 is geared as usual in a one to one ratio with shaft fill! which has a segmental portion 42 of slightly greater radius constituting a pinch bar mechanism. As is common in machines of this character, the tube is slightly retarded by this pinch bar mechanism thereby creating slack to enable the tube to assume the proper angle permitting severance against the serrated teeth of the former and the serrated teeth of the rotary lip knife. The former teeth are indicated at 44, Figure 2.

In the position of the tube as shown in Figure l, the segment 42 is just about to pinch the tube but neither wall of the tube has been severed. In Figure 2 the under wall of the tube has been severed against the serrated edge M of the former. This severance is brought about by a striker bar 45 which is similar to the striker bar shown in the aforesaid Poppe patent. As is usual, the striker bars 45 (of which there are two) are carried by a sprocket chain 66 which passes around upper and lower sprockets 41. There is a sprocket chain on each side of the machine and corresponding portions of these chains are connected by the striker bars E as is well understood in the art. The lower sprocket 47 is driven from the shaft 1 through gearing which includes the gear 48 and the ratio of gearing is such that the linear speed of the striker is greater than that of the feed rollers 33 or of the pinch bar mechanism. When the striker bar has reached the position shown in Figure 2, the serrated edge 31 of the rotary lip knife is substantially in line with the vertical diameter of the cylinder 35. Also pinch bar mechanism holds the tube taut while the striker bar causes the upper wall of the tube to be engaged against the serrated edge 37 by which the upper wall is severed.

It will thus be seen that mechanism is provided whereby the tube walls are severed one after the other and although the difference in time between the severance of the lower wall and the severance of the upper wall may amount only to a fraction of a second, it is nevertheless sufficient to give a greater ease of cut-off which tends to make the severing operation less noisy. It 15 also to be noted that the gear 38 is considerably larger than the gear 50, see Figure 6, which gear is on the end of the cylinder 34 and is engaged by one of the idlers 39. Therefore, the cylinder 34 rotates at a high speed compared to the pinch bar cylinders and since its direction of rotation is in the same direction as the feed of the tube, it does not retard the latter.

From the mechanism so far described, the rotary pinch bar by reason of its finer teeth compared with the teeth of the former, will produce a bag section having the appearance shown in Figure 5 in which the top edge 5| is provided with finer serrations than the top edge 52 which constitutes the wall of the tube which has been severed by the former teeth.

The invention further contemplates a construction whereb the former teeth may likewise be finer than has been heretofore necessary and to this end the construction shown in Figures 4, 6 and 8 i provided. In this construction the striker bar 45 is replaced by a roller 54 which may be of metal but is preferably of relatively hard rubber or at least provided with a surface of some resiliency compared to steel. The roller 54 is supported on a shaft 55, see Figures 4 and 6, which shaft passes through ears 56 formed in the links 51 of the sprocket chain 46.

It is contemplated that the roller 54 be located close to the edge of the former and spaced from it a distance slightly greater than the thickness of paper forming a bag wall. To this end the sprocket chain 46 is accurately guided during that portion of its travel when the roller 54 is in proximity to the edge of the former. To this end guiding members 58 are provided. These guides are slotted as shown at 59, Figure 4 and are secured to the side frames of the machine by screws 63 passing through the slots 59. The screw and slot connection provides for the accurate adjustment necessary to properly position the roller 54.

With the construction just described, the roller 54 severs the lower wall of the bag against the edge of the former as said roller reaches the position shown in Figure 8. In Figure 4 the lower wall has been severed and in a fraction of a second later the upper wall will have been severed by the rotary lip knife 36. Due to this manner of severing the lower bag wall, it has been found practically feasible to make the teeth of the former much smaller than has usually been the custom. The result of this construction is a bag section in which both walls of the severed section have relatively fine serrations at their edges. This is illustrated in Figure '7 which shows the upper portion of the section and in which the serrations 5| formed by the lip knife are matched by equal fine serrations 3i formed by the former teeth.

What I claim is:

1. In a bag machine, a former about which a web of paper is folded to form a bag tube, feed rollers for advancing the tube, pinch bar mechanism for creating slack in the tube, a rotary lip knife and connections from said pinch bar mechnism to said lip knife whereby it is rotated in timed relation with said pinch bar mechanism.

2. In a bag machine, a former about which a web of paper is folded to form a bag tube, said former having a cutting edge on its forward end,

a striker bar, means to cause said striker barely to touch the cutting edge of the former whereby one bag wall is severed as the striker bar passes the former and means for subsequently severing the other bag wall, the Walls being oiiset to produce a closing flap of substantial length.

3. A bag machine according to claim 2 in which the striker bar is in the form of a roller having a resilient surface.

4. In a bag machine, a former about which a web is folded to form a bag tube, said former having a serrated edge, a striker bar, means for guiding said striker bar so that it barely touches the edge of the former teeth whereby one bag wall is severed as the striker bar passes the former, a rotary lip knife located above the former, and means to cause said lip knife to sever the other tube wall subsequently to the severing of the first mentioned wall at the former.

5. In a bag machine, a former about which a web of paper is folded to form a bag tube, said former having a serrated edge, means for feeding said tube, pinch bar mechanism for feeding the tube at a slower surface speed than that at which the tube is fed by said feeding means, a striker bar for severing one wall of the tube against the serrated edge of the former and a rotary lip knife against which the other wall of the tube is severed while the upper wall of the tube is positioned between the edge of said lip knife and the former, the edge of said lip knife moving in the same direction as the tube is being fed by said feeding means.

6. In a bag machine, a former about which a web of paper is folded to form a bag tube said former having a cutting edge, feeding mechanism and pinch bar mechanism for said tube, a rotary lip knife situated above the former and spaced from its cutting edge, and means for causing engagement of said tube with said lip knife as said tube is acted upon by said pinch bar mechanism and when the severing edge of said lip knife is 

